Machine tool



Sept. 18, 1951 s, wlNCHELL 2,568,675

MACHINE TOOL Filed Dec. 51, 1946 5 Sheets-Sheet 1 INVHVTOR. ETERUN EWmnHEu. 30 By M, #W,

HTTEIFR'NEYS P 1951 s. F. WINCHELL 2,568,675

MACHINE TOOL Filed-Dec. 31, 1946 5 Sheets-Sheet 2 INVEN'TOR.

STERLIN EWINBHELL Fh-TuRNEys Sept. 18, 1951 s. F. WINCHELL MACHINE TOOL 5 Sheets-Sheet 5 Filed Dec. 31, 1946 L L E m m N \h M w l I i 5 N MN\ I E m N w m x M m e 5 w .m rl FIB! lk ll I aw v W O 11 O r 0 O T L QM 9 l l l l l l l 3; ll-IAIIXIIH IIIIIIIIIL W P 1951 s. F. WINCHELL 2,568,675

MACHINE TOOL Filed Dec. 31, 1946 5 Sheets-Sheet 4 IN VEN TOR.

EITERLINE] FWINEHELL Y HTTDR'NEYE S. F. WINCHELL MACHINE TOOL Sept. 18, 1951 Filed Dec. 51, 1946 5 Sheets-Sheet 5 INVENTOR. ETERLIN EWINEHELL BY A 1%,, m DRNE. 5

iateiifed Sept. 18, 1951 gterling F. Winchell, East Cleveland,

Ohio, as-

signor to The Warner & Swasey Company,- Gleveland, Ohio, a corporation of Ohio Application December 31, 1946; Serial No. 719,380 19 Claims. (01. 2947) 1 This invention relates to a machine tool and more particularly to an improved leading-on attachment for a machine tool which will enable the latter to be employed for cutting threads or the like.

An object of the invention is to provide a ma- ,chine tool, which as a Work spindle adapted to rotate a workpiece in opposite directions, a feed shaft rotatable in either direction in timed relation with the work spindle and a tool supporting member movable relative to said work spindle, with an improved means for moving the tool supporting member under control of a lead screw which is rotated in only one direction by the feedshaft regardless of the direction of rotation of the latter.

Another object of the invention is to provide an improved leading-on attachment for a machine tool which will enable the tool to be used for cutting threads, the attachment comprising a lead screw with which a tool carrying member of the machine tool is selectively connectible for unidirectional movement when the screw is rotated, and driving means for effecting unidirectional rotation of the lead screw in timed relation with the rotation of the work supporting spindle of the machine tool and regardless of the direction of rotation of the latter, whereby either right-hand or left-hand threads may be cut.

A further object of the invention is to provide an improved leading-on attachment of the type described in the preceding object and in which the means provided for effecting the unidirectional rotation of the lead screw includes a gear train selectively connecting the lead screw with the feed shaft of the machine tool, the gear train including a shiftable gear selectively positionable to transform bi-directional rotation of the feed shaft into unidirectional rotation of the lead screw, and a unidirectional clutch for preventing rotation of said lead screw in a direction opposite to said unidirectional rotation in the event the shiftable gear has been incorrectly positioned.

A still further obj eet of the invention is to provide a machine tool having a rotatable feed shaft and a movable tool carrying member adapted to be operatively connected with the feed shaft by a feed control lever for feeding movement of the member when the shaft rotates, with an improved leading-on device including a lead screw which is operatively connectible with the feed shaft for unidirectional rotation only, and means for operatively connecting the tool carrying member to the lead screw, the latter being provided with an n interlock arrangement with respect to the feed 2 a control lever whereby the tool carrying member cannot be simultaneously operatively connected to the feed shaft and the lead screw.

A still further object of the invention is to provide an improved leading-on device for the turret-slide of a turret lathe, the device comprising a lead screw rotated in timed relation with the rotation of the feed shaft by a gear train selectively operable by said feed shaft and provided with means for effecting unidirectional rotation of the lead screw; the device also including means for selectively connecting the lead screw with the turret slide to move the latter and means adapted to be automatically operated by the stop roll of the turret slide to disengage the operative connection between the lead screw and feed shaft when the turret slide has moved any given face of the turret to a predetermined position.

Other objects and advantages of the invention reside in various details of construction, combinations and arrangements of parts as will hereinafter become more clearly apparent to one skilled in the art from the following detailed description of a preferred embodiment of the invention described with reference to the accompanying drawings'in which: I

Fig. 1 is a front elevational view of a turret lathe, with certain parts omitted, and provided with a leading-on or threading device constructed in accordance with this invention;

Fig. 2 is an enlarged front elevational view of a portion of the right-hand end of the turret lathe illustrated in Fig. 1, more clearly illustrating the location and nature of the improved leading-on device;

Fig. 3 is a top plan view of the structure shown in Fig. 2 with portions of the casing or frame members broken away to reveal the internal structure;

.Fig. 4 is an end view, partly in section and partly in elevation, of the turret lathe shown in Fig. 1 and looking from the right of the latter, the view being on an enlarged scale and illustrating the segmental nut mechanism for operatively connecting the turret slide with the lead screw Fig. 4a is a fragmentary detached view, partly in section and partly in elevation, taken substantially on the line 4a-4a of Fig. 3 and illustrating the actuating mechanism for the segmental nuts in the lead screw engaging position;

Fig. 5 is a fragmentary end elevational view of the left side of the turret apron and the associated structure of the leading-on device;

Fig. 5a is a fragmentary detached view taken Fig. 8 is a fragmentary view, partly in section v and partly in elevation, the view being taken from the right side of the housing for-the gearing mechanism shown in Fig. 6 with a portion of the housing broken away;

Fig. 9 is a sectional View taken substantially on the line 9-9 of Fig. 7 and showing a pawl clutch mechanism with the parts thereof in engaged position;

Fig. 10 is a view corresponding to Fig. 9 but showing the pawlclutch disengaged;

Fig. 11 is a sectional view through a unidirectional clutch, the view being taken substantially on the line llll of. Fig. 7 l and showing the elements of the clutch in engagement;

Fig. 12 is a view corresponding to Fig. 11 but illustrating the elements of the unidirectional V clutch in disengaged positions;

Fig. 13 is a sectional view taken substantially on the line l3-l3 of Fig. 3; and

Fig. 14. is a sectional view taken substantially on the line l4-|4 of Fig. 13.

For the purpose. of disclosing the nature of this invention they present preferred embodiment thereof is illustrated and described as a device for use upon a turret lathe. It will, however, be apparent that the device may be employed upon machine tools of other types and the invention is not to be considered as limited to use with a turret lathe. Moreover, while the invention is illustrated and described as Preferably comprising a unitary attachment for use upon turret lathes, it will be appreciated that the device may be permanently incorporated in a machine.

tool at the time the latter is built rather than attached thereto at a later time.

In Fig. 1 of the ,drawings'there is illustrated a turretlathe of the ram type comprising a head 20 and a bed 2! having the usual ways upon which a base or ram-ZZmay-be adiustably positioned by conventional means. Slidably mounted ,uponthe base or ram is a movable member or turret slide, generally designated 23, provided with an indexible turret 24, the faces of which are adapted to support various tools. The head 20 is provided with the usual work-spindle and chuck 25 adapted to support a workpiece for rotation in either direction and at various speeds. Extending longitudinally of the bed 2! is a feed shaft '26 which is operatively connected with the work spindle for rotation in timed relationship thereto by conventional mechanism enclosed .whichis well known in the art, fortexample as isshown in PatentNo. 1,685,310 issued September 4 25, 1928 to E. P. Burrell et a1. As is customary, the lever 2'! is held in its operated or clutch engaging position by a catch pin which enters into a recess in the turret base. The turret slide 23 may also be moved by manual operation of a turnstile or hand wheel 28 connected upon the shaft 29 (see Fig. 14) which is employed for the power feed of the turret slide, the inner end of shaft 29 being provided with apinion 30 cooperating with a rack bar 3| fastened to the undersurface of the slide 23. It will thus be apparent that the movable member or turret slide is movable either towards or away from the head 20 by power or manual means in the conventional manner.

The tool supporting member or turret 24 indexibly mounted upon the turret slide 23 and is operatively connected, by means of a shaft 32 with a stop roll, generally designated 33. This stop roll is conventional and is provided with a vplurality of adjustable stop screws 34, there being one such screw corresponding to each of the faces on the turret 24. The stop roll is selectively indexed by the shaft 32, when the turret is indexed, to align a screw 34 with a movable stop block 35 which :is connected to one end of a knock-out rod 36 slidably supported in a portion of the base22. The inner end of the knock-out rod 36 is provided with a cam portion 3? (see Fig. 3) which in'turn cooperates with a knock-out pin 38 slidably. mounted in the base 22 and adapted to project into the opening or recess for the catch pinof the feed control lever 21. A spring 39, interposedbetween a portion of the base 22 and the stop block 35, tends-to move the latter to the right asshown in Fig. 13. A portion of the stop block 35 is provided with a surface forming an abutment against which that one of the adjustable stop screws 34, which is indexed into alignment therewith, may engage when the turret slide or movable member 23 has moved a predetermined distance corresponding .to the adjusted position of the screw. This engagement of the stop screw 34 with the stop block 35 moves the knock-out rod 36 to the left as shownin Figs. 3 and 13, thus causing the cam portion 31 of rod 36-to move the knock-out pinufifloutwardly with respect to the opening in which the catch pin of the control lever .21 isengaged, thereby displacing the said catch pin from the opening so that the feed control lever 21 will rock under the influence of gravity to disengage the ,power drive fro the feed shaft 26 to the pinionr3ll.

As is well understood in the art, the turret "24 may be indexed .to selectively bring the several faces thereof into operative position with respect to the worksp 125, and when so indexed the rod 'or shafti 32 will rotate the stop roll..33 to alignthe correspondingstop screw ,34 for engagement with the stop block35. In order to prevent rockingof the stop block 35, and to keep it in propenalignment with the selectively giiositioned stop screws 34, a pin 4B-is provided 'in the stop block and this'pin has a sliding fit in an opening formed in the base 22..

The leading-on device of this invention is adapted to beconne'cted with the base 22 and the turret slide23 and to cooperate with the automatic stopping mechanism just described. As is best shown in Figs. 2, 3 and,4, this attachment comprises a frame member, generally C ignated 4|, which is preferably attached to.a. boss ,on the rear portion of the slide 23 by'fastening means 42 which may-be machinescrews-or the like. 'I'he'frame 41 has a rearwardly'and forwardly projectingportion 43 which carries the mechanism for operatively engaging the lead screw of the device.

On the front'of the'turret lathe, adjacent the apron 45 for the turret, is mounted a gear-housing or support 46, forming a part'of the improved device, this housing being connected to the turret base 22 by means of a suitable bracket 41 and screws or other similar fastening means 48 (see Fig. 4) with the feed shaft 26 extending through the apron 45 and through the gear housing 46.-

Fig. 6. In another position thereof, the gear 49 is adapted to mesh with the gear 52 which is one of a pair of gears formed upon a sleeve 53, rotatably journaled upon a shaft 54, the other end of the sleeve 53 being provided with a gear 55 which is in continuous mesh with a portion of the wide faced gear 59. By this construction, it will be apparent that the gear 50 may be rotated in the same direction regardless of the direction of rotation of the feed shaft 26. Thus, for one direction of rotation of the shaft 26, gear 49 thereon will directly engage gear 56; and when the shaft 26 is to be rotated in the reverse direction, the gear 49 may be shifted to engage the gear 5'2, thereby rotating gear 55 and hence gear 50, the latter rotating in the same direction in both instances.

Shifting of gear 49 is effected by means of a forked shoe. 56 which straddles the gear 49 and is pivoted to the upper end of an operating arm 51, the lower end of which is connected to rock with a shaft 58. The forward end of shaft 58 projects through the front of the housing 46 (see Figs. 2, 4 and 6) and is provided with a handle or operating lever 59. This handle or lever is adapted to be rocked through an are over the face of an index plate 60 and is retained in'one of three positions by a spring detent 6| which may comprise a spring pressed ball cooperating with suitable recesses in plate 60 or in the face of the housing 46. The three positions for the handle or lever 59 may be indicated by suitable indicia, upon the plate 69 representative of the direction of rotation of thefeed shaft; for example, right hand, left hand and neutral. It will be seen that with the handle 59 positioned as shown in Fig. 2, in alignment with the neutral indication, the gear 49 is located out of mesh with respect to both the gear 52 and the gear 5| so that the latter is not rotated by rotation of feed shaft 26. By moving the lever or handle 56 to either of the other positions, corresponding with the direction of rotation of the feed shaft, the gear 49 will be correspondingly shifted to respectively engage it either directly with gear 50 or indirectly therewith through gears 52' and 55.

The gear 5|] is in continuous mesh with a gear 62 which is rotatable upon a shaft 63 supported in the housing 46. The gear 62 is provided with a cylindrical sleeve extension 64 forming one portion of a unidirectional clutch, the other portion of which comprises a slidable plunger 65 mounted within a transverse bore of the shaft 63. As shown in Figs. 11 and 12, the sleeve.

portion 64 of the gear 62 has a circumferentially extending slot 66 into which the outer-end of the plunger 65 may extend under the influence of a compression spring 61, one end of the latter being disposed within an axial-bore in the plunger 65 and the other end bearing againsta'pin or other retaining means 68. To prevent this extension of the plunger, the outer end thereof is provided with a tooth 69 having a width substantially equal to the width of the aforementioned slot 66 and less than the diameter of the main body of the plunger. The intersection of this tooth with the main body of the plunger forms a shoulder which engages with the inner surface of the sleeve 64 to retain the plunger within the trans-verse bore in the shaft. -The outer surface of the tooth 69 has a cam surface 10' on the one side and a notch 1| on the other side.-

This construction is such that when the gear 62 is rotating in a clockwise direction, as viewed in Fig. 11, the edge of the slot 66 will engage the notched portion 1| of the tooth 69 providing a driving connection between the ear 62 and the shaft 63. In the event the gear 62 is rotated in the opposite direction, the other edge of the slot 66 will engage the cam surface 10- on the. tooth 69, depressing the plunger 65 against the action of the coil spring 61 so that thegear 62. may now rotate relative to the shaft 63, as is. indicated by the positions of the parts in Fig. 12. This mechanism, therefore, constitutes a unidirectional clutch so that if the operator should inadvertently fail to move the handle 59 and thus shift the gear 49 to the proper position, corresponding with the direction of rotation of the feed shaft 26, the attempted rotation of the gear 62 in the direction opposite to that of its intended rotation will automatically disengage the driving relationship of the gear with the shaft.

The shaft 63 also rotatably supports a sleeve 12 upon the outer end of which is formed a gear 13. The sleeve 12 forms the driven member of a pawl clutch (see Figs. '1, 9 and 10), the sleeve carrying one end of a pin 14 which rockably supports the pawl 15 of the clutch. The other end of pin 14 is journalled in a collar 12a which is rotatably mounted upon the shaft 63; the outer face of the collar sliding upon the adjacent interior surface of the housing 46. Rotatably supported upon circular flanges of the sleeve 12 is an outer sleeve" 16 constituting the actuating member for the clutch and the latter is provided with ratchet teeth 11 on its outer periphery adjacent an end. The interior of the sleeve 16 is provided with an inwardly extending flange 11a which partially embraces an enlarged shoulder 18 upon the shaft 63, the latter constituting the driving member of the clutch. A portion of the flange 11a is cut away to provide a camshaped opening 19 within which the pawl 15 is positioned, the pawl 15, and flange 11a'preferably being the same width as the shoulder 18. This shoulder or driving member 18 has a portion of its periphery so formed as to provide a cam-shaped recess or notched portion 89 for interengagement with the tail of the pawl 15 to provide a driving relationship between shaft 63 and gear 13 carried by the sleeve 12. Extending substantially parallel with the shaft 63 is a pin 8|, one end of which is carried by the outer sleeve or actuating member 16, the inner end of the pin extending into an arcuate recess 82 provided in a flange portion of the inner sleeve or driven member 12. Disposed within this recess 82 is a coiled spring 83, one end of which engages an'end of the recess 82, the other end o th sprin enga ng th rin .,8l su m ng to produce relative vrotation between the-sleeves 12 and 76.

The construction of this pawl clutch is such distance, moving the latch member into firm engagement with a portionof the housing-J5, the spring 92 {and plunger 3! then functioningfto Bosnian the shock of this engagement between that with the .;parts as illustrated in Fig. 9 and 5 the l t h and thehousin'g. Rocking of the shaft .withthe shaft .63 rotating in the direction indi- .cated y .the arrow, the clutch is engaged so that the.ge ar 13, carried by the driven member or sleeve 12, is rotated. Thecollar 12a is also ,rotated since one end of pin 14 is supportedtherein. If the ratchet teeth H are now :held from rotation, rotation of the shaft 63 will tend to carry the pawl 15 within the cam shaped opening IQ of-the-actuating member or sleeve J6 At the same time the pin 8| will compress the spring 83. As the shaft 63 makes a partial revolutionrelative to the outer sleeve or actuating {member 16, the surface of the cam opening 19 will ,rcckthe pawl 15 to the-position illustrated in Eig. l0,'thus disengaging the pawl from the between collar IZ aand the housing 45. if desired the friction between collar 12a and the c singmav' be i c a d by sp n means acting therehetween which, howevenis not su flicient :tointerfere withthe rotationof the collar 12a wh nth c ut i en a e If the parts are positioned as shown in Fig li), with the shaft 63 rotating in the direction indicated by the arrow, the clutch may be reeng aged by releasing the ratchet teeth 11. The sp ring 83 will then act upon thepin-8l toproduce relative rotation between sleeves l2 and lfi moving the parts to the positions indicated in Fig. 9.

During the first portion of this ,movement the camshaped opening 79 will have rockedthe pawl 15 intoen gagement with the periphery of the collar l8'on the shaft-63 so that the tail ofthe pawl may be moved into the notch 80 when aligned therewith.

The illustrated meansfor selectively engaging the ratchet teeth "57 for stoppingthe rotationof the. latter is a toothedstop-member or latcht i .mounted for movement within. a recess in the housing 46. The outer endof this stopmember or latch is pivotallyconnectedto the upper end f of an arm 85, the lower endofwhich. is connected forrocking with a shaftBfi. Sh'aft BG is. also 7 provided with a second arm 81 connectedto. the

shaft for rocking therewith, arms 85 and 81 forming a bell-crank lever. The otherend of thearm 8'! is pivotally. connected to a vertically extending -linkp88, the upper end of which is pivotallycon nected to an arm 89 supported for rocking with a shaft. -Positioned in-aportionofthe housing 45 seas to be vertically above-thelatchffl isa plunger 9| normally urged downwardly by a spring 92. The lower end ofthe plunger 9| is adapted to eng ge'the latch 84 and position thela ter as shown Fi 9;Wh .n:t hfl t .90 has beenrocked to withdraw theiatch member .84. fr m the rat he teeth 1 Wh nth shaf 91 is. subseque tly rocked n a 1ienga ement fhla ch wit h r the latter wi c ntinue torctate fill gl9fi atchet teeth,

,9! is controlledby .the operation of the stop roll .mechanism 33 and by a manually operated control lever in a mannerto be hereinafter described.

As mentioned above, the sleeve or driven'memvber I2 is provided with a gear 13. This gear meshes with anidlergear 93 journaled upona stub shaft, the gear 93 in turn meshing with agear-95. The gear95has a sleeve-like extension 1 26 which rotatably' journaled in the support or housing. and in a plug l2! forming a portion of the housing, the plug .121 being provided ,to facilitate placingthe' gear in the housing during assembly. The lead screw 96 has a non-threaded portion of .reduceddiameter extending through the sleeve I26 and slidably keyed therewith, the end of this portion of the leadscrew extending exteriorly of the housing 4.6 and provided with'a threaded portion on which is screwed a nut I18 for a purpose hereinafter described. It will be seen, therefore, that rotation of the lead screw 96 is effected by the feed shaft 26 through operation of the gear train contained in the housing or support 46 (Figs. 6, 7 and 8) and this rotation of the lead screw '96 canbe effected inonlyone predetermined direction regardless of thedirection of rotation of the feed shaft 26. As noted above, the handle 59. and hence the .shiftable gear 49, is positioned to correspond with the direction of rotation of the feedshaft .26, and this will elfect the rotation of the lead screw 3 in the proper direction. In the event the handle 59 and gear llihave notbeenproperly positioned. the, unidirectional clutch will prevent rotation of thejscrew 9.6 inthe reversedirection. The rotation of the screw 96 may be terminated by either placing the gear '49 in neutral position or by operation of the pawl clutch illustrated in Fig.9

and .10 and which forms the driving connection betweenthe shaft 63' and the gear 13.

In order to effect an operative connection betweenthelead screw 96' and the turret slide 23 for moving the latter by rotation of'the former the forwardly projectin portion 43 of frame 4| is provided with means for engaging the screw 96 'in.threaded relationship. This meanspreferably comprises a pair of'segmental nuts 91 and-98 which are mounted for movement into and out of engagement withthe leadv screw upon diametrically opposed sides thereof in suitably shaped guides or openings provided in the portion 43 cf the frame. To effect this movement the segmental nutSl is provided with a pin 99 and the segmental nut 98 is provided with apin H30, these pins being received in angularly positioned slots .llilzand. I92, respectively, of a rcckable disk member I03. This disk member I03 is mounted concentrically withrespect to the lead screw 9.6 and is also provided with a radially extending slot. Ifll, in which is disposedan actuating pin H35 carried by oneend of a rockablearm I06." The other end of arm L06 is splined or slidably keyed tolarod or shaft ill!v extending substantially parallel. with the leadscrew 96.

It will' be apparent thatwhenthe shaft )1 is rocked in a-counterwclockwise direction, the pin I 0-5.wil l;;move the dis k. i 113 in aclockwise; direction so that the slots HI I and I112 .willact u on the pin and H10 new the eem a nit positioned and the screw '96 is in rotation, the nuts and frame 4| will be moved along said screw thus m ving the turret slide 23 under control of the lead screw 96; Rocking of the shaft I01 in" the opposite direction will disengage the segm n= ta1 nuts from the screw and discontinue this movement of the turret slide under control of the lead screw.

The rod or shaft I01 extends along the front of the machine tool and through the upper portion of the gear housing 46, the shaft being rotatably mounted therein and restrained from axial movement with respect thereto. The end of the shaft I91 within the housing or support 46 is provided with a rotatable member or collar I08, a portion of the surface of which extends through an opening in the housing 46 and is formed as a cam I09. The inner surface of the collar or member I and the portion of the housing 46 adjacent thereto are provided with suitable detent means H0 (see Figs. 2 and 3) for retaining the collar I08 and shaft I01 in either of two predetermined positions. Adjacent the collar l08 and riding upon the periphcry of the latter for actuation by the cam I09 is a ball-pin III carried by the outer end of arm H2, the inner end of which'is connected with the shaft 90 for rocking therewith.

The inner end of shaft 90 is provided with an arm member I I3'having a pm I I4 extending outwardi therefrom adjacent its outer end (see Figs. 5 and 13), this pin being received within an opening I I5 provided in a collar or enlarged portion H5 attached to the outer end of a rod H1. The inner end of the rod I I1 is threadably connected in the lower portion of the stop block 35, the rod H1 being guided for straight line movement under control of the stop block. As will be seen from Fig. 13, the spring 39 tends to urge the stop block 35 to the right, and is assisted by a rat trap type spring 8901.. (Fig. 3) surrounding a portion of the shaft 90 and having its ends connected with the arm 89 and a portion of the support or housing 46, respectively. Therefore, the arm H2 is connected through the shaft 90 and arm II3, enlarged portion H6 and shaft or rod II1 to the stop block 35 so that rocking movement of the arm I I2 will correspondingly move the stop block 35. Hence, when the shaft I01 has been moved to disengage the segmenal nuts from the screw 96, the cam I09 will rock the arm II2 thereby moving the stop block very slightly to the left as shown in Fig. 13. This motion of the shaft 90 will also operate through rod 88 to position the, latch 84 for disconnecting the pawl clutch and thereby stopping rotation of the lead screw 96.

Movement of the turret slide 23 may then be effected either automatically by the feed shaft 26 through the manipulation of the control lever 21 or by means of the hand wheel or turnstile 28. In the event feeding movement of the turret slide is effected by operation of feed shaft 26, the feed control lever 21 will be moved to the position indicated in Figs. 2 and 3 with the latch pin of feed control lever positioned in the recess therefor provided upon the base 22. This connects the drive train for the feeding movement to shaft 29 so that rotation of feed shaft 26 will rotate shaft 29 and pinion 30. The latter cooperates with rack 3| on slide 23 to effect a feeding movement thereof. When the turret slide has moved a predetermined distance by this driving means, contact of a stop screw 34 With the stop block 35 will operate throug the knock-out rod 36 and knock-out pin 38 to release the feed control lever 21 from its latched position, the latter falling by gravity to disconnect the feed shaft from the shaft 29. This operation of the stop block will, of course, rock the shaft 90 slightly with a consequent rocking of arm Il2 away from the cam surface I09 and the further removal of the latch member 84 away from the ratchet teeth 11. This additional movement has no effect upon the functioning of the device, and the parts are returned to their initial positions when the stop block 35 has returned to the position illustrated in Fig. 13 after the slide 23 has been moved to disengage the stop screw 34 therefrom.

Rocking of the shaft I01 for operation of the segmental nuts and of the collar provided with the cam I09 is effected by means of a handle or control lever H8 connected upon one end of a shaft II9 which is journaled in a suitable boss upon the apron 45. and extends through 7 an aligned'boss upon the support or gear housing 46. Upon the other end of shaft H9 is connected an arm I20, the outer end of which is pivotally connected with one end of a link I2I. The other end of the link I2I is pivotally connected to an arm I22fixed to the shaft I01. Hence, when the handle or control lever H8 is rocked, the shaft I01 is correspondingly rocked to effect movement of the segmental nuts 91, 98 and rocking of the shaft 90 for controlling operation of the pawl clutch, which in turn controls rotation of the lead screw 96. I

The control handle or lever H8 is provided. with an extension I 23 which overhangs a POI-.-

' tion of the feed control lever 21 so that the, latter may not be operated to effect feeding movement of the turret slideby means ofthe feed shaft 26 when the'handle orlever I I8 has been positioned to effect engagement of the nuts with the lead screw and rotation of the screw through the pawl clutch. In the event an attempt is made to employ the feed control arm 21 when the control arm 8 has been operated to effect movement of the slide 23 by means of the lead screw 96, the feed control arm 21 will engage the projection I23 before the arm 21 reaches its clutch engaging position. Conversely, if the feed control lever 21 be in operative position (i. e., with itslatch pin engaged within the recess of the base 22) an attempt to move the handle 8 for actuation of the turret slide by means of the lead screw mechanism will be prevented by the projection arm I23 striking the feed control arm 21 before the shaft I01 has been rocked sufficientlyto eitherengage the segmental nuts with the lead screw'or to engage the pawl clutch for operation of the latter. ;,The forward portion 43 of the frame H is provided with a pull pin I24 having a knob I25 on its outer end, the inner end of the rod extending within the frame below arm I06. As will be seen from Figs. 3 and 4, the guide openings for the segmental nuts 91 and 98 extend through the exterior of the frame member in order that the said segmental nuts may be readily placed and removed. The pin I24 being located under the arm I06 will, however, prevent the segmental nuts from being removed from their openings during the normal operation of the device, since the arm I06 willabut pin I24, thereby limiting the rocking of the disk I03 to an extent such that the pins 99 and I00 on the segmental nuts are retained within the angularly directed slots MI and I02. However, when the pin I24 is withdrawn from the path of the arm I06, the actuating handle IIB cannow be rocked sufficiently to operate through the intervening mechanism and rock the arm I06 to an extent sufficient to perm t the pins 99 and I to be removed from theslots IOI, I02. The segmental nuts may then be readily removed through the openings in the frame. The nuts are replaced bya reverse operation.

The lead screw 98 isalso'adapted to be easily replaced. As mentioned previously, this screw is provided with a portion of reduced diameter extending through the sleeve-like extension I26 formed inte rally with the gear 95, the shaft and sleeve portion being slidably keyed together and secured against longitudinal displacement with respect to each other by means of the nut I28 on the end of the lead'screw. It will be apparent that by removing the nut I28 the lead screw 96 may be pulled out and replaced by another lead screw if it be desired to employ a lead screw having a different thread.

In. the operation of a machine tool equipped.

thev operator will first index the turret 24 to. bring-the face thereof, which carries the threadcutting tool, intooperative position relative to.

the work spindle. He then adjusts the stop screw 34 corresponding to this turret face, to permit the desiredextentof travel of the slide 23 under control of the lead screw 96. The operator next positions. the handle. 59' in. alignment with that indic'iumonplate. 60 corresponding to the direction of rotation of the feed shaft 26; the direction of rotationbeingdependentupon whether right-hand. or left-hand, threads are to be cut. Thus, assuming the work spindle and feed shaft are rotating in a direction which would be productive of a right-hand thread. upon the work, the handle 59' will be moved to the position marked RH upon the plate-60, thereby shifting the gear 49 to the leftasseenin-Fig. '7 and en gaging this gear. directly with the wide faced: gear 50 (see Figs. Sand 8). The rotation ofgear 50 will drive-through gears 62,13, 93 and 95 to rotate the lead screw 96 for cutting a right-hand thread. Inthe event the: handle 59 had. been positionedv for a right-hand thread when the feed shaft 26 is rotated in a direction productive of a left-hand thread, theunidirectional' clutch interposed between gear 52 and shaft 63 will prevent rotation of shaft 63 andhence of the lead screw 96. r

In the event the work spindle and feed shaft are rotated in a direction for cutting a left-hand thread the handle 59 will be moved to align with the indication LE on plate60, thus shifting gear 49 from engagement with the wide faced gear 50 and into engagement with the gear 52. The gears 52' and being connected by sleeve 53 will rotate as a unit and, since gear 55 is in mesh with the gear'50, the resulting direction of rotation of gear 50'and' hence of leadscrew 96 will be the same as before. Here again, if the handle 59 has not been properly positioned in accordance with the direction of rotation of the feed shaft, the unidirectional clutch will prevent rotation of the lead screw 96. If it is desired to disconnect the driving connection from the feed shaft 26 to the gear train for lead screw 96, the handle 59 will be positioned in alignment with the indicium N, thus shifting the gear 49 to the position illustrated in Fig. 7 in which this gear screw 96.

is neither in engagementwith the wid'e 'faced' gear 50 nor the intermediate gear 52'.

After the gear 49 has-beenproperly. positioned, the operator will then raise the arm I I8 iupwardly,

I22 and shaft I01.

nuts 9! and 98 into engagement with the lead the collar I08 moving the cam I09. tothe position indicated in Fig. 5a. This movement of. the cam will'enable the arm II2 to rock in a counter-.

clockwise direction (Figs..2 and 3) under the influence-ofv spring 89a torock, the arm 89 thus raising the rod 88 with consequentrocking of the. arms 81 and 85 and withdrawal'of, the latch 84' from the teeth of the ratchet 11. When thelatch 84 has been thus withdrawn, the spring 83 acting throughthepin 82::wi11 rock the sleeve or actuating member I6 relative to the pawl carrying member I2 from the position indicated in Fig. 10- tov the position indicatedrin Fig. 9. The cam nuts in engagement therewith, the frame 4| i andv hence theturret slide 29 will be fed along the base 22 thus carrying the threading tool mounted on the turret 24 relative tothe work-which is supported and rotated by the work spindle and chuck-25.

indexed stop screw 34 has been set, the latter will abut the. stop block 35-moving it against the ten-v sion of the spring 39. This will move the rod I I! to the left, as viewed in Fig. 13, causing the arm ll3 tolrock the shaft in a clockwise direction.

As a result the arm 89 will depress the link.88,

therebyrocking arms 8! and 85 of the bell-crank ina counterclockwise direction, and moving the latch member 84 into the path of the rotating ratchet teeth 11. The latter will rotate through a slight, arcafter engagement of the latch 84 therein, moving the latter into abutting relationshipwith the frame .46 against the action of the spring-pressed plunger 9|. The shaft 63 will, however, continue to rotate and th pawl I5 will, therefore move relative to the sleeve or actuating member I6 until, the cam opening 19 has engaged the leading edge of the pawl 15 and movedit towards the center of the shaft, disengaging the tail of the pawl from the notch 80, as shown in Fig. 10. At the same time the spring 83 will have been compressed by the pin BI. This operation disconnects the drive to the lead screw 96'stopping movement of the turret slide. shaft 63 and the shoulder 18. thereon being free to continue rotationwithout effecting any drive of the lead screw.

The operator next depresses the handle I I8, thereby rocking shaft H9 in a counter-clockwise direction, the latter operating through the arm I29, link I-2'Iand arm I22'to rockithe shaft I01 in a clockwise'direction; as viewed in Fig. 4. This rocking. of shaft I01 will cause arm I06 to rock until it strikes the pin I24, therocking of arm I06 moving the disk I03 in a counter-clockwise direction thereby disengaging the segmental nuts 91 and 98 from the lead'screw'96. Clock- Rocking of. shaft I01 will also turn When the turretand turret slide have. moved the predetermined distance for which the:

wise rocking of shaft I01 will also rock the collar clockwise direction, under influence of spring 89a,

is limited by engagement of the ball-pin I I I with the cam portion I09. block 35 to occupy a position slightly to the left of its maximum right-hand position (Fig.

the distance between these two positions being equal to the movement necessary to effect disengagement of the drive for the lead screw. Although the stop block is so positioned, it is .11 within the conventional range in which it can be actuated by the stop roll, during automatic feeding movement of the slide by the feed shaft 26, to automatically knock-ofi the slide feeding movement through the cooperation of the knockout rod 35 and pin 38 with the feed control lever. 21.

ment of the pawl clutch and is provided because the operations following thread cutting on a conventional turret lathe are frequently a succes-' sion of feeding operations before a threading operation is to be again employed. When the turret is to be so fed, the feed control lever is operated in the conventional manner to engage its- 3%! This expedient prevents accidental engage- This will cause the stop adjustment of the stop screw 34 associatedwith that-face of the turret which is in operative position, this pin 34 will engage and move the stop block 35 thereby automatically knocking-off the feeding movement as previously described. A

However, in the event successive threading operations are to be effected, the parts of the leading-on or threading device, can be properly positioned by simply operating the handle II8 as. previously described. This will again engage the. pawl clutch and set the stop block 35 for automatically disconnecting the pawl clutch in the gear train for the lead screw, the latter operation being permitted by movement of the cam I09 out of engagement with the ball-pin III on the lever ll2.

As mentioned previously, the arm II8 controlling the operation of the improved threading or leading-on attachment is provided with an overhanging portion I23 forming an interlock with the feed control lever 21 so that the'mechanism for effecting a threading movement cannot be placed in operation when the feed con-' the extension I 23 upon the hande II8 'before thearm 21 reaches its clutch engaging position.

The turret slide may be returned to its initialposition after each operation by manual rotation of the turnstile or hand wheel 28. This manual movement of the turret slide can also be used for initial movement of the slide tobring the turret into cutting position.

It will be apparent that the improved device may be employed for cutting threads of different pitch by changing the relative speeds of the. work spindle and feed shaft by means of the. usual speed changing device provided in the conven'-' tional turret lathe. A further variety may be secured in the threads cut by employing different lead screws 96 and cooperating segmental nuts 91, 98, since these may be readily interchanged; the lead screw 96' being removed by simply removing the nut I28 and pulling the lead-screw shaft out of the sleeve I26, and the segmental nuts being removed by withdrawing the pull pin I24 and rocking the arm II8 an additional amount to effect disengagement of the pins 99 and I00 from the angular slots IIII and I32, new shoes being placed by reverse operation. When the pull pin is returned to its initial position, it will form an abutment for the arm I06 and prevent the segmental nuts 'being removed from the device.

While this invention has been described with reference to employment upon a turret lathe,

it will be apparent that it may be employed upon other machine tools, and that various modifications may be made in the construction and arrangement of the parts of the preferred embodi ment here illustrated and described. Therefore, the invention is not to be considered as limited tothe illustrated and described construction but only as required by the spiritand scope of the appended claims.

Having thus described my invention, Iclaim: lfA machine tool of the type described comprising a work spindle ada ted to selectively rotate a workpiece in oppositedirections. a mer'n ber movable relative to said work spindle and h provided with means for holding a tool or tools, a: feed shaft operatively connected with the work spindle for rotation in either direction in timed relation with the rotation of the work s indle,-

a lead screw, means operatively connecting said lead screw with said member to move the latter when the lead screw is rotated, and means for connecting said feed shaft with said lead screw for rotating the latter, the last-mentioned means including a selectively positionable member ada ted to effect unidirectional rotation of said screw regardless of the direction of rotation of the 'feed shaft and a unidirectional rotation ber movable relative to said work spindle andprovided with means for holding g to'ol on 'tools, a feed shaft operatively connected with the work spindle'for rotation in either direction in timed relation with the rotation of the work spindle, means for eifecting an operative connection of said member with said feed shaft to produce a normal feeding movement of said member when said shaft is rotated, a lead screw, means for opera tively connecting said lead screw with said memberto effect a threading movement of the latter when said screw is rotated, means for preventing simultaneous operative connection of said member with said feed shaft and With said lead screw,

and means for connecting said feed shaft with said lead screw to rotate the latter, the lastmentioned means including a selectively position able member adapted to effect unidirectional rotation of said screw regardless of the direction of rotation of the feed shaft, and a unidirectional rotationtransmitting device interposed between said selectively positionable member and' said screw'for preventing rotation of the latter. in the eventsaidpositionable'member has been positioned'to effect rotation ofsaid lead screw in *a'direction opposite to said unidirectional ro tation;

3; A- machinetool of'the type describedconk' prising a work spindle adapted: to selectively; rotate a workpiece in opposite directions, a mem---- ber: movable relative to said work spindleand provided with meansfor holding a tool or tools,

a feed shaft operatively' connected with the .work' spindle for rotation in either'direction inztimed relation with the rotation of the work spindle alead screw; means operatively connectingSaid lead screw with said member to move the'latter when said screw is rotated, and means fopconnectingsaid-feedshaft with said" lead screw to rotate the latter, the last-mentioned meansain eluding aselectively. positionable member. adaptedto eifect unidirectional rotation of said screw' regardless of thedirection of rotationofthe feed shaft, a unidirectional rotation transmittingdeviceinterposed between said selectively-position,-

able member and said screw for preventing rotation of thelatter in the event said-positionable. means has been positioned to effectrotation of saidlead screw ina direction opposite tosaid unidirectional rotation, and means responsive to a predetermined distance of movement 'of said movable member. to automatically terminate rotation of said screw by said shaft.

4. A machine tool of the type described in claim 3 and in which. the said means to automatically terminate. rotation of the lead screw by the feed shaftcomprises a clutch forming a part ofthe driving connection between said screw and shaft; said clutch including adriving member, a driven member, a pawl adapted to interconnect said driving and driven members, an

actuating member, resilient means connecting said drivenmember to said actuating member for normal rotation of said driven and actuating members-in unison and to permit relative rotationtherebetween, and means on said actuating member for moving said pawl to connect thesaid driving and driven members when said actuating member is rotated relative to said driven member in one direction and for moving said pawl to disconnect said driven member from said driving member when said actuating memberis.

rotated relative to said driven member in the opposite direction; and means automatically-actuated by movement of said movable member a" predetermined distance to selectively control said relative rotation between the actuating member and the driven member.

. 5. A- machine tool of the type described com-- prising a work spindle and a feed shaft operatively connected-for rotation in eitherdirectiong a tool carrying member movable relative to-said work spindle; means for operatively connecting said member with said feed shaft for producing a normal feeding movement of said memberwhen said shaft is rotated; a lead screw; meansfor operatively connecting said lead. screw with said member to effect a threading movement of'the latter when said. screw is rotated; means for preventing simultaneous operative connection of said member with said feed shaft and with said lead screw; and means for connecting said feed' shaft with said lead screw for rotating the latter' including a selectively positionable member adapted to effect unidirectional rotation of said screw reg'ardless of the direction of rotation of the feed shaft and a unidirectional rotation transmitting.deviceinterposed between said se le'ctively positionable member and said' screwfor preventing rotation of the latter in the event saidpositionable member has been positioned to eifect'rotation of said lead screw in a direction opposite to said unidirectional rotation; and a single means actuated by said movable member :when the latterhas moved'a predetermined distance to automatically disconnect the lead screw from'said feed shaft or said operative connections for effecting feeding movement of said movable member.

6. A machine tool of the type described comprisinga work spindle'adapted toselectively rotate a workpiece in opposite directions, a mem ber movable relative to said work spindle and provided with m'eans for holding a tool or tools,

a-fee'd shaft operatively connected with thework' spindle for rotation in either direction in'timed relation with the rotation of the work spindle, a-lead-screw', nut-means carried by said'memb'er and'selectively engageablewith said lead screw for operatively connecting said lead screw with sa'id'member to'move the latter when said screw is-rotated, and a gear train for connecting said feed shaft with said lead screw to rotate thelat-' ter, said gear train including a shiftable gear selectively positionable for" cooperation with either of two different gears in said train to effect unidirectional rotation of said" screw re-- gardless of the direction of rotation of the feed shaft; and a unidirectional clutch interposedbe tween said 'shiftable gear and'said screw forpre' venting'rota'tion of thelatter in the event said shiftablegear hasbeen positionedto'efiect rotae tion of'said lead screw in a direction opposite to said unidirectional rotation;

7. A machine tool of the type described comprisinga work spindle adaptedto selectively rotate a worltpiece'in opposite directions, a'member' movable relative to said work spindle and provided with means for holding a tool 'or tools, a feed. sh'a'ft' operatively 'connected'with 'the'work spindle" forrotation in either direction in'timed relation with the rotation'of the'workspindle, means'for" operatively connecting said member withsaid feed shaft for producing a normal feeding movement of said member when said shaft is rotated, a'lead screw, nut means carried by said member and selectively engageable' with said screw to effect a threading'movement of the member when said screw is rotated, means'fo-r preventing simultane ous operative connection of said member with said feed shaftand with said lead screw, and a gear train for connecting'said feed shaft withsa'id lead-screw to rotate the latter, said' gear train.

including a shiftab'le gear selectively positionablefor cooperation with either of two other" gears in said'train'to effect unidirectional rota-' tion ofsaid'scre'w regardless of the direction of rotation-of the feed shaft, and a unidirectional clutch interposed between said shiftable gear and ber movable relative to said work spindle and provided with means for holding'a tool'or tools; a feed shaft 'operatively connected with'the work spindle for rotation in either direction in timed second clutch and to be engaged and moved by member and operative connections between said in said train to effect unidirectional rotation of said screw regardless of the direction of rotation of the feed shaft, a unidirectional clutch interposed between said shiftable gear andsaid screw for preventing rotation of said screw in the event said shiftable gear has been positioned to effect rotation of said lead screw in a direction opposite to said unidirectional rotation, and a second clutch controlled by means externally of said gear'train; and means automatically operated by said movable member when the latter has moved a predetermined distance to disengage said second clutch thereby terminating the rotation of said screw by said shaft.

9. A machine tool of the type described in claim i8 and in which said means automatically operated by the movable member when the latter has moved a predetermined distance comprise interconnected shiftable elements supported up- 'on a relatively stationary part of the machine tool-with one of said elements cooperating with said second clutch to control the engagement and disengagement thereof, and a member ad- ,justably mounted upon said movable member and adapted to contact another of said shiftable elements and effect shifting of said elements when said movable member has moved the distance determined b the adjustment of said adjustable 'member.

10. A machine tool of the typedescribed comprising a work spindle adapted to selectively rotate a workpiece in opposite directions, a turret 'slide movable relative to said work spindle and provided with an indexible turret for holding tools upon the several faces thereof, a feed shaft operatively connected with the work spindle for rotation in either direction in timed relation with the rotation of the work spindle, a lead screw, means connected with the turret slide and selectively engageable with said lead screw to effect movement of the latter when said screw is rotated, a gear train for connecting said feed shaft with said lead screw to rotate the latter, said gear train including a shiftable gear selectively positionable for cooperation With either of two other gears in said train to effect unidirectional rotation of said screw regardless of the direc- "tion of rotation of the feed shaft, a unidirectional clutch interposed between said shiftable gear and said screw for preventing rotation of the latter in the event said shiftable gear has been positioned to effect rotation of said lead screw in a direction opposite to said unidirectional rotation, -a second clutchinterposed in said gear train, a stop, roll having a plurality of adjustable stop members thereon each corresponding to a face of said turret and indexible in fixed relation with the indexing of the turret, means supporting said stop roll for movement with said turret slide, and means to automatically disengage said terminate the rotation of said screw by said shaft when the turret slide has moved a distance corresponding to the adjust- ..ment of said indexed stop member, the lastmentioned means comprising a member adapted said indexed stop last-mentioned member and said second clutch to disengage the latter when said last-mentioned member is moved by said stop member.

11. A machine tool of the type described comprising a work spindle adapted to selectively rotate a workpiece in opposite directions; a member movable relative to said work spindle and provided with means for holding a tool or tools; a

feed shaft operatively connected with the work spindle for rotation in either direction in timed relation with the rotation of the work spindle; means for operatively connecting said member with said feed shaft for producing a normal feeding movement of said member when said shaft is rotated; a lead screw; nut means carried by said member and selectively engageable with said lead screw to effect a threading movement of the member when said screw is rotated; means for preventing simultaneous operative connection of said member with said feed shaft and with said lead screw; a gear train for connecting said feed shaft with said lead screw for rotating the latter including a shiftable gear selectively positionable for cooperation with either of two other gears in said train to effect unidirectional rotation of said screw regardless of the direction of the rotation of the feed shaft and a unidirectional clutch interposed between said shiftable gear and said screw for preventing rotation of the latter in the event said shiftable gear has been positioned to effect rotation of said lead screw in a direction opposite to said unidirectional rotation; and a single means actuated by said movable member when the latter has moved a predetermined distance to automatically disconnect the feed shaft from said lead screw or said operavtive connections for effecting feeding movement of said movable member.

12. A threading attachment for use with a machine tool having a work spindle adapted to selectively rotate work in opposite directions, a feed'shaft operatively connected with the work spindle for rotation in either direction in timed relation with the work spindle, and a slide provided with means for holding a tool or tools; the attachment comprising a frame member detachably connectible with said slide, a lead screw, a support detachably connectible with a relatively stationary part of said machine tool for rotatably 50 supporting said lead screw, means carried by said said lead screw for effecting movement of said frame member and selectively engageable with frame member and slide when said screw is rotated, and means for connecting said feed shaft 55 with said lead screw for rotating the latter, the

last-mentioned means including a selectively positionable member carried by said support and adapted to effect unidirectional rotation of said screw regardless of the direction of rotation of the feed shaft, and a unidirectional rotation transmitting device interposed between said selectively positionable member and said screw for preventing rotation of the latter in the event said positionable member has been positioned to effect rotation of said lead screw in a direction opposite to said unidirectional rotation.

13. A threading attachment for use with a machine tool having a work spindle adapted to se- ,1ective1y rotate work in opposite directions, a feed shaft operatively connected to said work spindle for rotation in either direction in timed relation with the work spindle, and a slide provided with means for holding a tool or tools; the attachment comprising a frame member detachably conqmnectible with said slide, a lead screw, a support detachably connectible with a relatively stationary part of said machine teol for rotatably supporting said lead screw, means carried by said frame member and selectivelyeng; 'able with said lead screw for effecting m ementorsaie frame member and slide when said screw isrbtated, and means for operatively connecting said feed shaft with said lead' screw for rotating the latter, the last-mentioned means including a selectively positionable member carried by said support and adapted toeffect iinidirectional rotation of said screw regardless of the direction of rotation of the feed shaft, a undirectional rotation transmitting device interposed between said selectively positionable member and said screw for preventing rotationof the latter in the event said positionable member has been positioned to effect rotation of said lead screw in a direction opposite to said unidirectional rotation, and

means actuated bysaid slide after the latter has moved a predetermined distance to automatically terminate rotation of said screw. 7 a

14. A threadingattachment of the type defined in claim 13 and in which said means for automatically terminating rotation of said lead screw by said feed shaft includes a pawl clutch comprising two rotatable meinbers adapted to rotate together or relative to each other, a pawl pivotally mounted on one of said rotatable members,

means on the other of said rotatable members adapted to engage saidpawl to rock the latter in one direction for effecting clutch engagement and in the other direction for effecting clutch disengagement, and means cooperating with said members to cause relative rotation therebetween for effecting rocking of said pawl;

15. A threading attachment ,of the type described in claim 13 andiri which the said means to automatically terminate rotation of the'lead screw by the feed shaft comprises a clutch forming a part of the driving connection between said screw and shaft; said clutch includinga driving member, a driven member, an actuating member, resilient meansconnecting said driven member to said actuating member for normal rotation of said driven andactuatin'g members in unison and permit relative rotation therebetween, and means on said actuating member for moving said pawl to connect the latter with said driving member when said actuating me mber is rotated relative tosaid drivejn 'memberjin one direction and "for disconnecting said pawl from said driving member when said actuating member is rotated relative to said driven member in the opposite direction; and means 'automatically actuated by movement of said movable member and cooperating with said clutch to selectively control said relative rotation between the actuating member and the driven "member.

16. A threading attachmentfor use with a machine tool having a work spindle adapted to selectively rotate work in opposite directions, a feed shaft operatively connected to said work spindle for rotation in either direction in timed relation with thework spindle, a slide provided with means for holding a tool or tools, means to operatively connect the feed shaft to thefslide for producing a feeding movement of the latter and stop means actuated by the slide when the latter has moved a predetermined distance to automatically disconnect the operative connection and terminate the feeding movement; the attachment comprising a frame member detachably connectible withsaid slide, a leadscrew, a

support detachably connectible with a relatively 7 2O stationary part of said machine tool for retatably supporting said lead fgrew, means A car'- ried by said frame meniber and selectively engageable with said lead screw for effecting movement pf saidfrafne memberyand slide when said s'crewis rotated, means fer preventip simultaneous engagement of said selectively engageable means With the lead screw and the operative connection of the feed shaft with the tool slide, me'ans for connecting a feed shaft with said lead screw for rotating thelatter, the lastmentioned means including a selectively p05 tionabl member carried by said support and adapted to effect unidirectional rotationof said screw regardless of thejdirection of rotation of the feed shaft, a unidirectional rotationv transmitting device interposed between said selectively positionable member and said screw for preventin'g rotation of the latter in the event said positionable member has been positioned to effect rotation of said lead screw ina direction opposite to said unidirectional rotation, and means cooperating with the means for connecting the said shaft with the lead screw and actuated by the stop means of the machine, tool. when the slide has moved a predetermined distance to automatically terminate rotation of said screw by said shaft. v

1'7. A threading attachment for use with a machine tool having a work s mcue adapted to selectively rotate work in.'opposit'e directions, 'a feed shaft operatively connected to said work spindle for rotation in either direction in timed relation with'the work spindle, and a movable slide provided with means for holding a tool or tools; the attachment comprising a frame mem ber detachably connectible with said slide, a lead screw, nut means carried by said frame member and selectively engageaplewith said lead screw to effect movement ofsaid frame member and slide when said screw is rotated, a housing detaehably connected with a relatively stationary part of said machine tool and adapted to rotatably support said lead screw, and a gear train in said housing and adapted to operatively connect "said feed shaft to said lead screw for rotating the latter, said gear train including a shiftable gear selectively positionable for cooperation with either of two different gears of said train to effect unidirectional rotation of said lead screw regardless of the'direction of rotation of said feed shaft, and a unidirectional clutch interposed between said shiftable gear and said screw for preventing rotation of the, latter in a reverse direction in the event said'shiftable gear has been positioned to effect rotation of said lead screw ina direction opposite to said unidirecti'onal rotation. 7

1:8. A threading attachment for use with a machine tool which has a movable tool slide and a feedshaft rotatable in opposite directions, said attachment cdfnprisingaframe member 'detachab l y conliectible with Said Slide, "a housing "member adapted to be connected to a relatively stationary portion of the machine tool, a lead screw rotatably iournale'd in said housing, nut means carriedby said frame member and selectively erig'agea'ble with said lead 'SC'IeWtO effect movement of said frame member and slide when said serewiis rotated, a

gear train in said housing adapted to opera- "tivelyconnect said feed shaft to said lead screw vf Ma n the i rr's ari a l "a smrtame g'ear selectively "positionable rereaoperation with either of two different gears of said train to efiect unidirectional rotation of said lead screw regardless of the direction of rotation of said feed shaft, a unidirectional clutch interposed between said shiftable gear and said screw for preventing rotation of the latter in a reverse direction in the event said shiftable gear has been positioned to effect rotation of said lead screw in a direction opposite to said unidirectional rotation, a second clutch in said gear train adapted to be controlled by means externally of said gear train, and means cooperating with said second clutch and engaged by said slide when the latter has moved a predetermined distance to efiect disengagement of said second clutch thereby terminating the rotation of the lead screw by the feed shaft.

19. A threading attachment for use with a machine tool which has a movable tool slide and a feed shaft rotatable in opposite directions, said attachment comprising a frame member detachably connectible with said tool slide, a housing member adapted to be connected to a relatively stationary portion of the machine tool, a lead screw rotatably journaled in said housing, nut means carried by said frame member and selectively engageable with said lead screw to effect movement of said frame member and slide when said screw is rotated, a gear train in said housing including gears operatively connected to said feed shaft and to said lead screw respectively, a unidirectional clutch in said gear train permitting 22 only unidirectional rotation of said lead screw regardless of the direction of rotation of said feed shaft, a second clutch in said gear train including two relatively rotatable members rotatably mounted upon a shaft of said gear train, a pawl pivoted upon one of said members and adapted to provide a driving relationship between said one member and shaft, a camming surface on the other of said rotatable members adapted to move said pawl into and out of driving engagement with said shaft, resilient means extending between said rotatable members tending to rock the said members in a direction to effect driving engagement of the pawl with said shaft, means cooperating with the said other of the rotatable members and actuated by said slide when the latter has moved a predetermined distance to restrain rotation of said other of the rotatable members and thereby disengage said pawl from said shaft.

STERLING F. WINCHELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 736,792 Search Aug. 18, 1903 80 2,100,899 Burger'et a1. Nov. 30, 1937 2,154,546 Van I-Iamersveld Apr. 18, 1939 2,286,715 Cheever June 16, 1942 

